1. Field of the invention
This invention relates to a method and apparatus for protecting and maintaining shorelines, and more particularly to such a device for growing aquatic vegetation in soil-filled, wave energy-absorbent pilings.
2. Discussion of the Background
Wave and current movements cause erosion and sedimentation where water transfers energy to shorelines. Typical methods of halting this process fall into two categories. Sheet piling and retaining wall methods place a barrier that reflects wave energy, by providing a vertical surface at the land/water interface. Riprap or revetment construction methods employ a sloped hard surface to achieve the same result. The construction elements used for the above methods are rarely in harmony with nature, as corrosion-resistant materials available are generally employed in their construction. These methods of construction have resulted in vast stretches of shoreline that have no natural interface where land and water meet, and which do not take advantage of energy-absorbing properties of natural materials. In addition, wave reflecting construction practices typically lead to greater erosion adjacent to them, where the energy has been redirected. There is a need therefore for a stabilization method that is wave energy- absorbing, natural, and can be integrated into a structural design sufficient to withstand strong water forces.
U.S. Pat. No. 5,178,489issued to Suhayda discloses a shoreline protection technique that incorporates used automobile tires into walls or baffles used to absorb wave energy, divert water, and trap sediment. According to Suhayda, the tires are anchored to a water body bottom via pilings 58. However, Suhayda fails to incorporate natural materials, and contributes to water pollution by submerging automobile tires into water.
U.S. Pat. No.5,338,131issued to Bestmann overcomes some of the problems associated with traditional methods of shoreline protection. Bestmann discloses a shoreline construction technique that incorporates precultivated, emergent aquatic plants whose roots are held within a water-permeable, biodegradeable vegetative carrier system, and other botanical elements to protect shorelines. However, according to Bestmann the botanical elements are anchored by varying methods of staking the elements into the shoreline, a labor intensive approach which provides limited wave energy resistance. For example, Bestmann discloses an aquatic plant 14 rooted in a plant plug 12 which is disposed in a substrate 31. However, substrate 31 is disposed flush with the existing shoreline, and horizontal at its upper end, thereby offering little or no wave energy absorption. The elements used by Bestmann, such as "layers of biodegradable non-woven felt" and "geotextiles" can be cost prohibitive for large projects. Furthermore, biodegradable felt is a temporary stabilization measure meant to retard erosion only until it has biodegraded, after which it provides no further stabilization properties. Using such materials and methods requires extensive regrading of the shoreline area to create a nearly flat shoreline, which is labor intensive and cause erosion in and of itself